Hillingdon Council cannot deal with any informal requests in terms of estimated costs. You would need to seek your own legal advice from a solicitor and valuation advice from a qualified surveyor.
Provided that you have had the lease for a minimum of two years, you have the right to extend your lease by 90 years in addition to the remaining unexpired term and to have the ground rent reduced.
How long is left on my lease?
You should have been given a copy of your lease when you purchased the property or, if you have a mortgage, your lender may hold this.
You may be able to obtain the information from Land Registry. Charges are available on the Land Registry website.
What to do next
A formal notice needs to be served on the council. This is called an 'initial' notice.
The notice should be addressed to
Borough Solicitor Hillingdon Council Civic Centre High Street Uxbridge Middlesex UB8 1UW
Once you have served the 'initial' notice, you would also have to pay the council's legal and valuation costs. These will vary depending on individual circumstances, but are likely to be a minimum of £2,100.
If you withdraw your request, you would still have to meet any reasonable costs. In response to the notice, the council has to serve a counter notice, within approximately two months. This is the council's offer to you to extend your lease by a further 90 years.