Quick google produced this from the Home Owners Alliance
"Some estate agents have been reported putting pressure on people to use their mortgage service, saying they will get preferential treatment or, worse, claiming they are unwilling to work with them unless they do. Putting undue pressure on you in this way is illegal. By all means, get a quote from the estate agent’s mortgage adviser before shopping around, but bear in mind that:
they may have a far narrower selection of mortgages than if you look further afield
there may be an upfront charge for their advice whereas some mortgage brokers and banks can give you mortgage advice for free.
Also be aware there have been accusations of mortgage brokers and estate agents working closely together, openly discussing potential buyers’ budgets in order to get as much money out of the buyer as possible. So again, find out what deal they can offer while remembering that you are under no obligation to accept their mortgage offers.
For more on this read our guide “Why you should avoid estate agent in-house services”
. . . So basically you can play along saying that you are happy to receive a quote from them but only if there are no upfront fees. But note the bit about them pressurising you being illegal. Don't know the details about that, but google could help you out again . . .
HTH