"1. Do we need a solicitor?
2. If we do need a solicitor, would it be as expensive as selling a house?"
1. Yes.
2. Without knowing the ins and outs, its impossible to say. If the title is registered, is in the uncles name etc.,etc it will cost but not as much as if the title is a mess and the legalities were not completed 30 years ago, which is entirely likely.
Do some basic homework and ask some local solicitors for a quote. You will also a land registry compliant site plan to complete.
mf