I think you should look for another starter kit, something reliable and that is branded and easy to use. A pico new user setup springs to mind. You don't have to buy the latest and greatest, but they do make some good starter kits on a reasonable budget. I am partial to the Aspire Zelos as it has great battery life, easy operation, can do temperature control (you probably don't want to worry about that-- yet) and is very light and portable. .Comes with the Nautilus 2 tank which is a MTL tank but does also have a 0.7 coil which can technically be a DL tank, but one of the lighter, less cloud producing ones.
PG/VG ratio does matter, your PG seems high to me, but you can experiment and see what suits you best. I think a better setup and the right ratio of PG/Vg will give you more satisfaction. I vape 15--18 mg nicotine in my MTL tanks, and that does the trick for me. If you're able to wait a bit, you will find cheaper prices online, but I'm not sure exactly of the status of importing gear into England as they have TPD regulations. With that said, that means more vape shops, usually, find one where the staff present know what you are talking about when you spit out those brand names, and can demonstrate various setups.
I am happy to get a week out of a coil unless I run the Nautilus 0.7 coil (which I do like, I set it up with airflow and watts to still be able to MTL but the flavor and coil life are extended). That said, I'm sensitive to PG, and use 100% VG, which is a gunking factor for me. With my factory coils, when they go bad, I soak them in VERY HOT h20 to start, and then let them sit overnight. I rinse and then set outside to dry, I'm usually able to get another 4--5 days out of them, which does reduce my costs, so it's worth it to me. Sweet or dark juices will gunk up my coil even MORE, but I don't worry too much as I'm DIY juice now and I minimize those factors. But, you can find a storebought juice that is clear and vapable. I'm partial to coconut and brandy, if I use storebought juice, and my favorite storebought is coco which I may use on special occasions, but it is a true coil killer, LOL. I purchased a coco flavoring for my DIY and at my next DIY session, I plan to try and make it WITHOUT all the extra sweeteners and see how I do.
Good luck!
Anna