I am a beginner like yourself and have found this forum really helpful. Having recently gone through the same decision making process I thought I would give you my thoughts.
The package you are looking at seems great. My package was similar although I went for a 6.5m rig as my conditions are light to medium coastal wind conditions. I soon realised that I needed a smaller sail (now have 5.0m and 5.7m sails) and am on the look out for a 7.5m for those sunny but light wind days when you really want to get out. This should cover most conditions that I encounter.
Therefore, I would check with other local sailors as to likely conditions and buy a sail the right size for learning at your particular ability level. I too had a go at windsurfing on holiday in St Lucia around 8 years ago. I took up the sport in the UK last year and had 6/8 lessons on my local windsurfing school kit. I then purchased my own kit.
My main worry was buying a board that was either too advanced for me to progress on or too forgiving that I out grew it too quickly. What size is the Go that you are thinking of buying? Learning boards tend to be 200/220 litres but are huge and relatively heavy. You are likely to out grow these very quicky but are stable and great for getting the basics down to start with.
I did this and then purchased a Carve 145. This was pretty challenging for me to begin with but given a Summer's sailing I am so glad that I went for it! It is really good fun and will challenge me for some years to come I think. If I do eventually get a smaller board, the Carve will come in for lighter wind sailing.
Exact board size depends upon your size, weight, experience, type of conditions(salt water is more bouyant than lake etc - is it choppy or flat etc) what level you are aiming to get to, but there are far more expert people here that can go through this with you in detail.
My advice would be do a little training on the school kit(which will get a bit bashed in the process) then when the basics a down, buy a board which will challenge but not take all the fun out of it which could be demoralising. To give more accurate advice on the precise size and type board the guys will need a little more info I am sure.