Should I wait until I finish foundation training?

Not necessarily, and the honest answer is that it depends on what you are trying to buy rather than on what a lender will allow.

You can get a mortgage on a foundation training contract. That part is settled. Waiting is not a requirement, and an adviser who tells you to come back in a year has probably not checked. What finishing training changes is the size of the number, not whether there is one.

When you move from foundation into an associate post your income usually rises, sometimes substantially. If the property you want sits at the very top of what you could borrow today, another year of earnings may be what gets you there, and waiting is a decision rather than a defeat. If it sits comfortably inside what you can borrow now, waiting buys you nothing and costs you another year of rent.

There is a second thing waiting changes, and it cuts the other way. Once you go self-employed some lenders want a full year of trading behind you before they will look at you, and some want two. So there is a window just after foundation training where the employed evidence has gone and the self-employed evidence does not exist yet, and borrowing can be harder in it than it was during training. A larger deposit bridges that window – there are lenders who will drop the trading-history requirement at around twenty per cent down. Buying before you move, buying with a bigger deposit, or waiting until the accounts exist are all workable. Drifting into the window without having decided which is not.

So answer the property question first. Find out what you could borrow today, then decide whether waiting gets you something you actually need. That is a short conversation, and it is worth having before you spend a year acting on a decision nobody has checked.