Is 3 month work ok to put down on a CV?

Hey there you awesome people! Thanks for taking the time to click on the question

Your intelligence that is much higher than mine will be needed now

I’m 19 going to be 20 in February, live in London

I’ve had 2 weeks work experience (with my school, helping elderly people)

I’ve worked 1 year in a restaurant (Friday, Saturday and Sunday) no p45 or anything just salary as cash in hand.

I then moved to another restaurant and worked there for 1 year same thing.

I now am working in Subway but I’m going to leave after only working there for 3 months, I’m leaving because I’m going abroad for 6 to 7 months with my grandma. Subway created a P45 and all those documents that you guys know better than me.

I have a reference from my last restaurant work

My question is that I would like to get a reference from Subway, but would it look ok or bad if I put down worked at Subway for 3months?

My CV work history will look something like this:

2 weeks work experience (2009)

1 year worked in restaurant (2011-2012)

1 year worked in restaurant (2012-2013)

3 months worked in subway (2013-2014) (Leaving in January)

I think the only work that will appear on a background check will be Subway because they created a P4. The restaurants where just cash in hand no pay slip nothing, just turn up work for 3 days then get paid by the boss. I do have the restaurant as a referee if needed.