I suggest you read "5.2 Assessment regulations relating to taught students" of
this document. The key parts (with emphasis added by me) are:
(b) Stage requirements
must be met before a student is permitted to progress to the next stage.
(c) Where a student has failed modules as a result of failed or missed assessments, and no exceptional circumstances claim has been accepted (see Regulation 5.6), and the stage requirements cannot be met, defined
re-assessment opportunities are permitted on one occasion only. Re-assessment is defined as an opportunity to redeem failure for the award of credit to meet progression or award requirements. Re-assessment opportunities at each stage of every award are defined in the Guide to Assessment, Standards, Marking and Feedback.
If we then check the "Guide to Assessment, Standards, Marking and Feedback",
here, we find some wiggle room. Are the six modules of equal size, so worth 20 credits each? Let's assume so, and let's assume that of the three which you're potentially going to fail, you actually only fail two. So you fail two modules, worth a total of 40 credits. In this scenario U2.2.4 applies, which means you'd
still receive credit for the failed modules:
"U2.2.4 Compensation in Bachelors Programmes
a. In stage 1, if a student fails one or more modules (i.e., achieves a module mark below 40) in the stage s/he may
still receive the credit for the failed module(s) and progress provided that:
i. s/he has failed no more than 40 credits; and,
ii. no module marks are lower than 30; and,
iii. the rounded credit-weighted mean over all modules taken in the stage (including the failed module(s)) is at least 40."
From what you've said, conditions ii and iii will be met. So you just have to worry about whether you fail more than 40 credits or not. If you do, then we're into reassessment territory. However, that the resit
doesn't necessarily have to take place during the August resit period:
"U2.3.6 Resits for overseas students
All candidates are normally expected to attend resit examinations in York on the scheduled dates. Departments may be given the opportunity, however, to make a special case for overseas students to take resit examinations at a later date, or for visiting students to take resit examinations at an earlier date than other candidates, provided they are prepared to produce special question papers for the late resits and provided the arrangements are approved in advance by the Chair of the Standing Committee on Assessment."
If you don't manage to make yourself available for the reassessment opportunity for some reason, of if your department aren't prepared to "produce special question papers for the late resits" then clause 4.17 kicks in:
"4.17 Repeat Study
Undergraduate students whose stage 1 results, after compensation and reassessment, do not meet the requirement for progression into stage 2 are now
normally permitted to repeat the whole of stage 1, provided they have a minimum credit weighted mean of 10 marks."
You might want to take a look through those two documents yourself, just to reassure yourself that the above is an accurate reflection of their contents.