Whilst Lincs is correct that your development is now under the control of the FA, that doesn't mean that your own county can't help you. Some will offer mentoring and coaching to new level 4s by people who have been there and done it, but even if they don't that doesn't stop you asking for help from current or past level 4s or above. It is completely different refereeing at that level to what you have been used to, and as Lincs says the observers are much better trained and told to spot everything and act accordingly. He won't be wandering around the pitch, rather will be sat in the stands often with an elevated view, and there really is no hiding place. The players are also much more "referee smart" and will seize on any weakness to use it to their advantage, many of them will be older players who have previously played at a much higher level. I can remember as a L4 refereeing Junior Lewis, and he had been playing in the Premier League two years earlier. As a level 3 I refereed James Scowcroft a few times, and both of these players were smart around how they dealt with me (even though I sent the latter off ..!).
So you really need someone to help you out, watch a few of your early games to offer advice, and even just be available to have a chat on the phone after things have gone wrong in a game or you are unsure of something. Also I would say forget about your observer marks in the first season, it is very rare for new L4s to get promoted and you are safe from demotion for a year. It might sound a bit daft, but you want to be getting your mistakes out of your system in the coming season so that come March 2018, when you no longer have protection, you aren't making them anymore. It has also long been thought that some observers mark 1st year referees lower as they know they can do so to keep their average down but without affecting the referee. It shouldn't happen, but two observers have told me personally that they do it, and it definitely does happen.