I always thought that as a low hours SEP PPL without IR(R) or IR, I would never plan a flight where I HAVE to be anywhere specific, by any specific time, and/or HAVE to come back to anywhere specific by any specific time on any given day.
If on the day, the weather looks good, the F214 & F215 look conducive for flight, then look at METARs and TAFs at or near departure and destination. If the journey is long enough to warrant it - also have a look at METARs and TAFs at places on route. I then also generally quantify my reasoning with any other weather sources that I can get my hands on, MetOffice, BBC, Wunderground...etc... To make a decision - if all else works - then and only then GO.
Your plan A should always be an alternative method of transportation, until such a time as you have a CPL ME IR and fly a big jet, where reliability will be as good as the airlines. With each stepping stone along the way, you'd be able to increase the likelihood of doing the flight but never be 98% sure.
Tay Cough - makes a good point about pushing your comfort zone, but this should ONLY ever be done when you don't have to be anywhere - GetThereItis is something you absolutely want to avoid at all costs.
If the weather is marginal, and the trend isn't going to block you out - you can always "give it a go" and worst case, just come back, if nothing else, its a good learning point!