Use a site like booking or similar to 'reserve' a hotel without a deposit that can be cancelled anytime. Once you have the visa you can change where you will stay. On arrival you'll only need a hotel name and town for the immigration landing form but even that doesn't mean you actually have to stay there. All hotels 'should' report who is staying with them with 24 hours of arrival.
You don't need a Thai contact. We left the line blank.
. The British car license allows you to ride a moped (less than 50cc) without a test in the U.K. only. It does not translate to riding a 'scooter' of any description in Thailand where, I believe, there is no difference in motorcie' for license purposes. So, the British license along with the IDP will only cover you if you have passed the test in U.K. for a motorcycle. No U.K. Motorcycle (over 50cc) license means you need a Thai license.