OP, everything5pounds.com is a fucking revelation. They have amazing dresses, skirts, jeans, etc for, yes, £5 each. Yeah the quality isn't that durable and you might have to chuck it after 4 washes, but for £5 just think of it as renting an outfit for a special occasion. Their sizing is on the tight side so if you are a 12-14 then order a 14, etc.
As far as the sex side of things is concerned, nothing is more sexy than enjoying yourself, and letting him know. Be vocal, ask for what you want (I know this is really scary if you're not used to it, but you might not ever see this guy again, so what the fuck, right?) Tell him - put your finger in my pussy/arse/mouth, lick my clit slowly/fast/gentle/firmly. Pinch my nipples, slap my arse, pull my hair, gently caress me, blow in my ear, fuck me hard/slow/gentle/quick.
And ask him what HE likes too! When you're sucking his cock, ask him if he likes the shaft licked, his balls licked (spoiler: he will), does he like you to wank the shaft as you suck him, does he like it if you try to get it all in, etc. If he's circumcised and you don't have any experience of that, ask him what works best.
The key to a great sex session is communication. Ask for what you want! Tell him what feels good! Enjoy!