There's no reason not to do this. On the other hand there's nothing terribly motivating it either.
If you consider that power costs are a more general problem that you can solve with solar who cares if you're powering mining, your fridge, lighting, etc.

If pricing in the UK is an issue, just going into solar would help your costs anyways, that is if it were less expensive/you had more sun. Maybe a backyard generator, I think those do something like 500 watts depending. Or as a completely different alternative, just invest in one of the many securities that are for mining that include somebody else's (presumably less expensive) electricity. There are several on btct.