It gets seen as a grey area, but the law affects the purchase / sale to over 18s only
Possession / ownership isn’t covered by that so it is seen as legal for an airsoft to be gifted to you before you are 18
There must be no payment or other ‘compensation’ otherwise it wouldn’t qualify as being gifted
Though gifting is seen as a grey area, in a slightly unrelated / semi related situation recently in paintball the UKPSF (recognised representative body for paintball) have consulted a barrister on legislation and ‘gifting’ to under 18s was seen as legal
PS
I trust that you are / will be over 14?
There could be other legislation that could affect possession if you are under 14