Written Britons looking to do up their kitchens with a remortgage loan may want to get a fixed deal quickly.According to moneysupermarket.com, lenders will start pushing up the interest rate on fixed-rate mortgages as predictions about an increasing base rate continue.Finding the funding to renovate a kitchen could therefore become tricky unless homeowners take action now.Louise Bond, Head of Mortgages at moneysupermarket.com, said fixed-rate mortgage products have been falling for the past two years.But now the bottom of the mortgage market has been reached, she claimed.She added Borrowers looking to fix should lock in quickly, before the next tranche of mortgage products come through showing drastically increased rates.And improving a kitchen could boost the value of a home.The latest housing index from Halifax revealed that the cost of a property increased by 2.6 per cent in May - to stand at 158,565 - when compared to April.