Would need more detail. House size, year built. Any upgrades done? Etc

Property was E1 on sale. It should have come with an Advisory Report indicating potential improvements. Any house can be brought up to an A rating, the question is whether the upgrades can be afforded or are worth doing? Most likely requires upgrading of floor, wall and roof insulation, heating system and controls, and glazing.

Quote #3: 310

For onsite survey and providing all recommendations on achieving an A rating, incl VAT

Quote #4: 305

Anything can go to a A but it depends on what works are feasible and the costs. You'll need a very good heating system. You could possibly look at getting a heat pump. You'll need renewables too such as solar panel. You'll also need wall and roof insulation and good doors and windows. If you're even considering a heat pump you'll need a technical assessment done first so make sure that whatever quote you accept is also a heat pump technical advisor. I am one and a BER assessor.