Helium balloon will take space tourists into the atmosphere

Why go through training and tandem jumps to become a skydiver when you can have the "same" experience in a wind tunnel on the ground?

Btw: being in a "basket"/capsule underneath a balloon at the "edge of space" does not provide weightlessness, so you really can not really compare those experiences with each other.

Many people associate space flight with ballistic rockets. As much as they want to go to "space", they want to experience their "Right Stuff" childhood fantasies.

I can't believe I missed this...

£90k is far, far too high a price, especially for only 5 hours. You could purchase an actual ride into space for that amount.

Knock the price down, lower the altitude so you can carry more passengers and make it safer, and then I'd invest. Spending a couple of days at 20km altitude would be worth a few grand per person at least, especially with the black sky above you and the blue ball of Terra below you. You could take maybe 20 passengers up, with a lounge area (with bar) surrounded by personal cabins. Maybe charter the entire thing out occasionally.

If you can charge £2k/person, and do 3 flights a week, that's £60k a week. A single craft might be able to gross £3 million/year. Enough to be economical? I think so. It might be possible to lower the cost to several hundred pounds and still turn a profit, though your cabin crew aren't going to be able to be on every flight due to limiting radiation exposure...