Hi CHT,
It looks like you've already received some great advice. However, I asked our Head of Professional Services, Roger Doncom, to see if there's anything else to consider. He said the following:
"Both methods are employed – however, in the case of extending the lease prior to the sale, be careful that a Freeholder doesn’t take advantage of a 'need for speed' and ask for more than should be paid. This could ultimately delay or complicate the sale. For this reason, it is more normal for the seller to serve notice to extend between exchange and completion to ensure the sale isn’t held to ransom by an outside party. With this in mind, the purchaser needs a formal, professional valuation to establish the best price."
If you'd like any further advice, feel free to contact Roger - his details are on this link
http://www.marshandparsons.co.uk/services/professional/
I hope the purchase goes smoothly.
Kind regards
Liza-Jane Kelly, Marsh & Parsons