How conservative did you need to be? Bought this house for £280k Feb 2020. Valued at £375k in May 2021. Being redone again tomorrow and no idea where that will be but another around the corner in a worse location just went for >£400k but did have planning for an extension. I was hoping to be able to put down at least £360k as will get me to a much better bracket or could release equity and let the Mrs have her new kitchen...
Someone better informed than I can give you a better answer - our mortgage broker indicated that a great deal will be based upon the most recent sales down your road, and then compare them to your house.