You cannot get a normal mortgage on a Park Home, as you would on a brick built house. This is because a Park Home is still legally classed as a Caravan.
There are specialist companies that will provide finance to purchase a park home that is under 14 years old, but the interest rate will be slightly higher than you would expect to pay on a mortgage.
There is a really good website that explains all of this, along with the ins and outs of buying and selling a park home. Its called www.parkhome-living.co.uk
Hope that is of some help to you