International Tracked is a new Royal Mail service....it is fully tracked at 5 points and there is online confirmation of delivery.  You do not sign for it.

Only your seller would know if it complies with the UK rules for paypal protection.

There is a service of International Signed For which is only tracked in the UK and you do need to sign for it.  From an experience some 18 months ago it is not acceptable for paypal seller protection.....I got a refund, seller lost their money.

There is also another new service called International Tracked and Signed.....I guess it is the best of both systems as you would have to sign for it and it would be fully trackable.

Only your seller would know which service is going to give her paypal protection.