I know a suit's jacket can not do a blazer job but he is just a college student. Unless suit's the dress code, he can wear t-shirt for a comfortable look. It may look refreshing in your eyes but might not in his 18yo friends.
If it's your first suit and you have sufficient budget, try a made-to-measure store in real life. Most of them are regular fit so unless you live in US, you will find these online suits are baggy. Some of my friend in fashion industry said that regular fit is getting more and more attention, let's wait for it.
How about a navy with pinstripe? You're kidding right? Expecting to buy something in London cheaper than online :D Now, if I really want to buy something in London, I would definitely go for a good shoe and then try to find a custom suit with price about £600. btw, I'm Andy from Sydney. Nice to meet all of you!