You may be asked - I think it depends on whether your bank think it is potentially suspicious or not - I don't believe there is any obligation to inform the taxman of deposits of a certain size. A one off lump sum is hardly the activity of a professional money launderer and your bank will probably think along those lines too.
Tax liability can be worrying when you sell a property abroad. It needn't be. Just remember, in nearly all cases you sent the money out from a UK bank to buy the property. That is on record, just like the returning lump sum is. The most important point here is that the money you bought the property with was UK tax-paid money.
i.e. You already paid all liable taxes on that cash once, they can't tax you again because it is coming home. Capital gains is another matter (often not relevant these days sadly) but if the money you return isn't more than the money you sent out all those years ago, there is no case to answer m'lord!