Hiya!
I'm surprised yer better half doesn't know anyone! certainly in the Indian community there's no shortage of builders! and what with families knowing familes and the tendancy for us Indians to build an extension the size of a small african country to any properties we own, I'm sure he could put the word out amongst the proverbial Indian Aunty/Uncle grapevine and get a good list of recommendations!
Can't forget good contacts within the Polish community too! plenty of construction workers all over London, and a good proportion of them with their own registered business's etc.
The Polish guy I know I can recommend, if you want, I can sort out a meeting with him if you'd like. The Caveat I always put through is that it's best to be there whilst work is carried out - seeing as many of the 'workers' themselves have little or no English speaking skills, when it comes to construction at home, a good bit of direction is required!
For the work you've said - I know they can do it for a reasonable (although even the Polish builders have begun jacking up prices over the last couple years!) price.
Let me know!
Cheers, DtM! West London & Slough UK!