Although the checked bag allowance (if you purchase this option) is 20kgs, you can buy extra weight at the time of booking in 3kg increments for around £21 per 3kgs. However, the maximum weight allowed for any bag is 32kgs (which I believe is set on behalf of the health of the luggage handlers).

And to clarify - if you were to buy two hold bags it would only entitle you to check in two bags with a combined weight of 20kgs (i.e. 10kgs each).

Extra weight as pre-declared specific items of Sports equipment is much more cost effective.

From what I understand, Ryanair will soon be allowing the option of purchasing further bags, each with their own 15kg maximum. Easyjet may follow suit eventually.

Watch out if you want to get an Easybus to London. policy is 1x20kgs bag and 1x5kgs bag