Before purchasing tickets for Take That concert or any other for that matter, do the following:
Get the sellers tel no & address and check out it is genuine! Also ask for a work number and check out how long they have worked there.
Make sure they have tickets paid for and can provide the transaction details with the ticket company with a reference number which has their address and email.
Do not think recorded delivery will be of much guarantee because envelopes can contain anything, not necessarily tickets. If you claim there were no tickets the seller will deny this and say you must have sold them on.
Pay by credit card so you are covered because if you buy way in advance, (tickets are not usually available until a few weeks before the concert), the claim period through resolution centres for ebay (60 days) or paypal (45 days) will have expired. In addition, the time for leaving negative feedback will have expired.