You usually get paid at your normal time, whether you are in work or on holiday. For most people this is the end of the week or month. Some companies may choose to pay some form of advance holiday before you go but that's a matter for them. There's certainly no legal requirement to pay at any time other than your normal pay date.
My boss pays holiday pay every week. Apparently he'd employed one or two people who had taken holidays and then left, but hadn't been with the company very long, so they had taken eg a years entitlement in holidays when they'd only been there for six months. As a result he now pays pro rata holiday pay every week! It does mean when we're on holiday that we don't get any pay though.
You get your basic wage for the weeks you are on holiday and entitled to be on holiday, (does not include overtime if you usually work it unless average hours stated in contract). Some employers will pay holiday pay when you have not worked long enough for the entitlement, they assume you will work for the full period, but if you leave, any overpaid holiday pay will be deducted from your final pay.