The best way from London to Bicester (if you really have to go there) starts every half an hour or so from Marylebone.
Failing that, from Chalfont & Latimer - Amersham, The Lee, Wendover, Aylesbury, turn right off the A41 as soon as you can after Aylesbury, then Quainton, Marsh Gibbon and Bicester. It's probably flatter than Dodo's route. And despite my cynicism it's a very nice ride but you'll need your wits about you to dodge the potholes.
If you're starting from a different Chalfont - climb up as soon as you can onto the ridge road that goes up from Denham past Denham Golf Club station and use that as a route into Amersham.
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I notice you're OK with hills. From Amersham dive down into Great Missenden, then take the road towards Butlers Cross past Chequers, then up to Stone. Along a bridleway (very good tarmac) to Eythrope Park, turn right down towards Waddesdon, straight over the A41 to Quainton.