Yes, if you have an offer that will complete within 3 weeks.
The alternative (and only worth considering if you have plenty of equity in your property) is to arrange a bridging loan.
As an example, If your house is worth �200,000 and you have a mortgage of �100.000 on it, if the Bank repossesses the house, they will sell at auction as soon as is realistic. This may only net �150,000 leaving you with �50k.
If you take bridging loan out, it may cost you a fair bit (typically fees of 2% monthyl interest), but in 3 months you can probably sell it for more through an estate agent than you can at auction.
If you want further details, go to www.allianceandgeneral.com