His age shouldn't be a barrier.
If he's got a good credit rating he should be able to borrow up to about £65,000 without much difficulty, and possibly up to £90,000 if he shops around.
Remember though that most lenders will require him to have enough savings to pay for at least the first 5% (and possibly up to 10%) of the house price.
So, if he's got some savings and lives where house prices are relatively low he stands quite a good chance of getting a mortgage. If he's got no savings and lives in London he probably doesn't.
http://www.moneysavingexpert.com/mortgages/how-much-mortgage-borrowing#