Probate is really simple as some of the above have suggested. You WILL need probate because there is land involved (the Land Registry will not register a change of ownership without a Grant of Probate in these circumstances).
First you need to acquire the original Will. Keep it safe, do not mark it and do not even attach anything to it with a paperclip.
Then you write to all the asset holders and ask for a balance at the date of death, same with the liabilities. You will need a valuation of the property which you can get from a local estate agent. You need this to fill in the Return of Estate Information for HMRCS.
When you have collected all the information, call the Probate Registry. You attend for an interview with one of the Registrar's and as long as the paperwork is in order the Grant will be issued.