I'm a light classical soprano with a bit of an obsession with Emma Kirkby! I trained at City Uni/Guildhall on their joint Masters programme a few years ago, and would love to perform recitals/concerts with a lutist - preferably someone in the area, as I have a day job which limits my time considerably. I'd also be interested to find out whether there was any contemporary music for soprano and lute as well...
re your query about contemporary (and classical) pieces for soprano/lute, you could try Chappells of Bond Street (although they're now in Wardour Street). They have the most extensive sheet music collection (other than somewhere like Amazon, which isn't all in one place) in the UK. The good thing about Chappells is that they don't discard their stuck and so there are hidden gems there that have been sat for 20/30 years waiting for someone to buy.
If you've not been (which I'm sure you have?), it is WELL worth a visit. As a kid I used to spend many a Saturday morning at Chappells 'trying out' the sheet music that I couldn't afford to buy on their pianos - they never seemed to mind sheet music browsers back then!
Best of luck - hope you manage to find a lute player - sorry, I don't play!