Before that a little bit of context:
I am about 6ft tall and the last time I checked, my weight was about 80-82 kg (176-180 lbs). I am quite a beginner, in the sense that I have got a few lessons at beginner/advanced beginner level and practiced a bit. So, I have basic notions on how to stand on the board, to turn etc. However, I am quite inconsistent at the moment and I would like to be able to practice longer and more often, to improve that, before passing to take intermediate level lessons. However, I feel I cannot do that quick enough if I just hire the equipment. This essentially is because of 3 reasons:
1. the current hiring system allows me to have 2 slots of 2 hours per day at a fixed time. which means that, if I am available later than any of the 2 slots, I cannot hire the board. Also, If I am free for the whole day, I am limited in using my board, as there is not an option for a daily rent (like for example for the snowsport).
2. if it is a good surfing day, it is likely all the equipment has been booked and, therefore, even if I am free, I cannot surf.
3. the cost. Hiring regularly would cost me quite some money and, probably a month or 2 would buy me a decent foamie.
Therefore, I am considering buying myself a softboard to increase the amount of time I could spend practicing. The problem is that I live in a flat with limited space and I go to the beach by public transport, so anything from 6ft upwards would be unpractical for both transporting and storaging and anything below, apparently, from what I read, is not suitable for my experience level. I found a 5'6 42 L softboard on the web, but I do not want to invest money on it (as surfboard are pretty expensive

What should I do? is it really that difficult to practice on a board shorter than 6 ft? Did any of you had the same problem? And, if so, how did you manage to solve it?
Many thanks for your answers and apologies if my English is not correct, but I am not a native speaker.