Yes, the Options are transferable. You can grab an Ad Option for the amount you desire, sit on it and see how Houser.co.uk grows.
With time, as Houser grows, so will the value of advertising on the site. You can then approach a business that markets to the property industry and possibly sell your options.
For example, if you grabbed an option for £1,000, the actually money that will be deposited in the account when option is exercised is £5,000. You can sell the option to third party for £250 or any mutually decided amount. The new owner of the Option will spend £250 with you and will deposit £1,000 with Houser.co.uk but will get £5,000 in his/her account to advertise on Houser.co.uk.