You will have absolutely no problems, easy for trains in from Maidenhead, and as TBM says, 90% of Reading fans will be on the non stop services from Reading. There will be some that get on from suburbs like Tilehurst on the stoppers, or woollyback Royals from more remote/posher parts of Berkshire, but you won't get any trouble, especially if you are wearing your colours.
May the best team win, so long as it is Reading, please God for once!