One of the things that makes this forum such an valuable source of information, is the sharing of facts between the posters. So for the benefit of the original poster, and others who may have similar questions, I will try and answer them briefly.
First of all with regard to your housing arrangements, your creditors will be prepared to support a reasonable amount of housing costs - be it by way of a mortgage or rental for you and your family. They will not expect to support other family members at their expense - so your Mum would need to be paying a proper market rental for your property, which would need to be taken into account for the purposes of calculating your disposable income. Of course so would the mortgage payments.
With regard to your other queries:-
1 Your car could be at risk if creditors feel it is of excessive value and a more modest car might be requird to be found. You would also need to check the terms of the finance agreement to see whether it is HP or just an unsecured loan. If the latter, then payments towards the loan would cease under IVA proceedings.
2 An IVA is unlikely to affect you getting visas to travel in foreign countries.
3 If you are living together as a couple, your fiance's income would need to be taken into account within the calculation of disposable income available to offer to creditors, but then so would her personal expenditure and repayments towards her own debts.
4 Your budget is worked out simply on what you spend on a regular basis, and what you need to save as contingency expenditure for things that are not paid regularly, such as car tax, or simply to meet miscellaneous unanticipated expenditure.
5 Apart from usual and reasonable contingency allowances, you would not be allowed to retain any disposable income without good reason.
6 If you are provided with vouchers by your employers, these can be spent as they would be treated as gifts.
7 Under IVA proceedings you are required to have your property revalued during the final year of the IVA, with a view to seeking new lending of a maximum 85% loan to value. If, by raising a new mortgage, you would be left with funds in excess of £5,000 - having paid off your existing mortgage and secured loan - then you would need to introduce the surplus into the arrangement for the benefit of creditors. The monthly cost of your new lending would not be expected to exceed more than 50% of your then current IVA payment.
As Philip has already advised you, it can be difficult to deal with specific circumstances on a public forum, and a lot of the areas you need advice on are private. I suggest that you contact an insolvency practitioner who will spend time with you exploring the options, and advising you of the advantages, disadvantages and implications of each one so that you can decide on an appropriate way forward.
The very best of luck in your search - in the knowledge that the first step - of recognising a problem and sharing it with others who can help you has already been taken.
Regards, Melanie Giles, Insolvency Practitioner
