The Real Thing, Old Vic, London<br/>Counted?, County Hall, London<br/>Pressure Drop, Wellcome Collection, London

A Stoppard revival and a docu-drama about young voters' disenchantment bump up against the latest in a wave of works to tackle the rise of the BNP

Love is rarely simple, and The Real Thing is complicated, both sexually and theatrically.

In Tom Stoppard's award-winning romance from 1982, revived at the Old Vic, Toby Stephens plays Henry, a witty star-dramatist. His thespian wife Charlotte (Fenella Woolgar) is apparently committing adultery, except – we subsequently realise – it's happening in a play-within-the-play, House of Cards penned by Henry.

Meanwhile, off-stage, he and another actress, Annie (Hattie Morahan), have fallen headily in love. After moving in together, they will remain true. Unless, that is, Annie's fears regarding Henry's fidelity are proven right, or she ends up being seduced by someone else – perhaps the actor who's cast as her clandestine lover in 'Tis a Pity She's a Whore.

Art and life are amusingly and painfully entangled. Moreover, there is an additional teaser here: Stoppard's intimations of autobiography. Obviously, The Real Thing isn't a wholly faithful docudrama, but Stoppard had left his first wife to marry his second in the Seventies. And his next well-known amour was Felicity Kendal who created the role of Annie.

Morahan is superb in Anna Mackmin's new staging, with just a trace of Kendal in the mischievous humour. What's fascinating is her mercuriality: playfully flirtatious yet also highly strung and strong willed.

Even so, this production may mildly disappoint Stoppard devotees who still treasure the memory of the 1999 Donmar revival, where Stephen Dillane was achingly brilliant as Henry. Stephens doesn't quite manage the plunge from droll self-assurance to poignant heartbreak. Mackmin also plonks him centre-stage for Henry's bouts of extended philosophising. Put thus on an implicit pedestal, those speeches sound awkwardly like a smug authorial set-piece.

That said, Stephens and Morahan are a sexy pair. He delightfully captures the ease with which Henry can be an intellectual, jokily lewd and ardently sensual – especially when she is larking around, flashing in a silk dressing-gown while he is trying to type. At bottom though, this touching play is about mutability and enduring devotion, passion and artful pretending.

Counted? is a verbatim, political documentary play, performed by the troupe Look Left Look Right in the former, real-life debating chamber of London's County Hall. Taking the floor in this small but splendid space – all leather benches and marble arches engraved with "Ayes" and "Noes"– the young cast re-enact interviews conducted with a range of British citizens (different races, classes and ages).

Fundamentally, Counted? is anxious that a large percentage of the electorate – particularly the young – feels no urge to vote. Evidently, this show has been timed to coincide with the election campaign. Ironically though, it already seems out of date, after this week's surge of Cleggmanic headlines.

Still, that is a media storyline yet to be proven at the polls, and Counted?'s research is still of serious import, finding widespread disillusionment and ignorance. In one arresting vignette, a young working-class mother doesn't even know what a ballot box is. A group interview with descendants of legendary suffragettes sharply encapsulates our depoliticised state too, with one teenage Pankhurst declaring that voting makes no difference.

Simultaneously, through the disgruntlement, you can see the seeds of renewed engagement emerging: a repeatedly stated desire for local communal action; the striking suggestion that "None of the above" should be a ballot-box option to give a voice to mass discontent, and a plea for polling stations to be less drab.

The drawback is that the script editing and the acting is hit and miss, under co-directors Ben Freedman and Mimi Poskitt. Home Counties oldsters are impersonated particularly unconvincingly. And Simon Pollard is an irritating eager-beaver as the fictionalised Professor Elliot Wilson – nothing like the project's principal researcher, Professor Stephen Coleman of Leeds University, who is far more sagaciously mellow discussing this project, on video, on the web.

Pressure Drop is the latest in a wave of plays tackling the rise in support for the BNP. What's most winning about the Wellcome Trust's first theatre show – a collaboration with writer-director Mick Gordon – is that it's a multimedia experiment, with Billy Bragg gigging, live, between scenes. This in the same week as the veteran musician and left-wing activist made headlines for having a face-to-face row, on a street in Dagenham, with the BNP London Assembly member Richard Barnbrook.

Now, in a long, darkened gallery, the promenading audience gather around his band and other mini-installations on raised podia: a glowing chapel with a coffin; a tawdry pub and a living room. Gordon's drama is set somewhere rather like Barking (Bragg's Essex birthplace). Michael Gould's working-class, white Jack is enraged by economic hardships and "raghead" immigrants taking over. So, he's about to sign up as a BNP candidate, encouraged by his motor-mouthed, loutish mate, Tony (a comical, then scary, David Kennedy). Jack's long-estranged and now cosmopolitan brother (Justin Salinger) is appalled when he returns for the funeral of their father. Pip Donaghy's Ron pops out of his coffin to reminisce about how he always loved the harmoniousness of reggae and ska hits like "Pressure Drop".

Gordon's script needs paring and tends towards PC didacticism. Nevertheless, his cast is strong and Bragg's folk-punk ballads manage to be rooted in Englishness without bigotry. His band's cover version of "Pressure Drop" leaves you wanting to party.

'The Real Thing' (0844-871 7628) to 5 Jun; 'Counted?' (0844-482 8008) to 22 May; 'Pressure Drop' (0844-412 4318) to 12 May

Next Week:

Kate Bassett treads carefully as Women Beware Women, with Harriet Walter, storms the NT