Should i take this chance?

Rite, long story shortish; Have had a crush on girl for 6 months or so, we have been friends for a bit and get on well but she sends mixed signals and i have never been confident enough to ask her out. BUT on wednesday we are going to a university open day just us two and we will be in another city for the whole day and iam really tempted to say something but i don't know how or when would be appropriate, any advice? Thanks in advance