Not allowed to take my son away in this Country

last week I asked my ex if I can take our son to Liverpool to see his grandparents for 3 days. She had totally ignored my request and has come back to me and said "no" what can I do?

I get one weekend off in seven and normally have my son on days off. But she has said because it falls on a weekend she is having him as she never sees him. (Just every single night after work)

There are no courts orders in place at all. She is just being unreasonable.

Can anyone offer any advice?

Well you could try to get a contact order, but you may find that if you go down that route that she becomes even more awkward. How old is your son? Is he able to have a say in what he wants? Perhaps you may be better to accept this and look at other ways and times that you could make the trip. If your son is at school then during school holidays may work. If you give your x a few alternative dates then it would prove that she was being unreasonable if she said no to them all. Would advise that you keep a diary of events so that if you do end up going for a contact order it will prove that you need to have something set down to enable reasonable to be established.
It would undoubtedly be better if you could sort something out between you, but the next step would probably be mediation rather than going straight to court. Mediation may be a good way forward if there are ongoing issues, but if this doesn't happen too much and contact is going ok otherwise then it may be worth just putting up with it and trying to get the visit to your parents organised in other ways. It does seem unreasonable if she is insisting on every weekend and you aren't getting any. If this is the case it may be worth pointing this out in a way that isn't going to get everyone upset.

Janey