I only use this sim when I travel, I'm about to arrive in UK so Ive recharged my sim but the plan does not register in my profile, continues to show as "all used"
Sounds like it has gone into hibernation.
When did you last use it for a chargeable action? EE PAYG SIMs are deactivated after 6 months of non-use. You then have a further 3 months to call EE to reactivate it before it is lost completely.
You needed to make a chargeable action like making a chargeable call or text, topping up or buying a Pack or Add-on, not just using your mins, texts or data from your pack.