Monty Python Live (Ticket Help!)

[Sundae]

I'm not asking for anyone to book tickets for me.
In fact I need to have my own details on the receipt to ensure I can claim 50% back through one of our work benefit schemes.

I will be in the right place at the right time - not at work, on payday, debit card ready and phone and internet access. I only want one ticket.

But please, please, please can anyone help me in HOW to actually book it?
The O2 direct website information seems to suggest you are best calling a number for AX (?) but doesn't say why. The tips websites say book online and keep trying but don't say where. I have to be careful I am buying a ticket through the correct channels or 50% refund will not happen.

I don't book tickets myself. Well, I haven't in years, so it's new to me again.

Can anyone savvy with this just wade through the layers and tell me what I need to be doing at 10.00 GMT on Monday? I'd like a reasonable seat, but hype says I'll be lucky to get a ticket at all. Whatever. It's on my birthday and I have binoculars

Cheers.