All NATS staff are eligible for concessionary travel and deals through a NATS Travel Club. It's not the same as having an interline concession such as some airline staff might have, but it does at least offer some 'perks' through certain airlines, holiday companies, hotel chains, etc. See Touchdown World Travel Services for some examples of what is on offer.
Additionally, ATCOs can join UKATTS and/or GATCO which offer further industry 'deals'.