How would I market my business?

Well, the first thing you need is some holiday homes on the site.

And then you need a marketing budget. £ 1000 / month would be a decent amount to start with. There are a lot of competitors, all with deep pockets. If you do not have the funds to compete, then you do not have a business.

And anything with 4U in the domain name is doomed to fail from the beginning.

I'm sorry to be so negative but you do not have a business. All you have is a basic WordPress site.