Amanda,
like other have said its not an issue unless between now and IVA approval you were planning on keeping credit file on a good state for some reason. As soon as you miss a payment you probably won't hear much, miss two might get reminders and card maybe gets blocked until payment. You might get a phone call from the bank or credit company asking to speak to you about your account, if you keep failing the security check when they ask you to confirm your date of birth address etc then they can't verify its you to speak to the account about
Seeing as you have found this forum now, is as was said above, a good time I decide if you're progressing with a credible firm. Have a real careful read of your agreement and the protocols the agreement relates to.
let us know which firm you're liaising with and also read the proposal very careful if you're at that stage, you also want a company that doesn't charge statutory interest (like Mcambridge Duffy) and one that is not bound by the 2014 protocols, which could be a real big issue in 4 years if you have a property.
interest is important in the rent you came in to money, Inheritance, Payrise, Windfall etc
If the company you are loading with say the interest and protocols are not relavent to you they are lying.
If you share the company you're thinking of going with long term posters here can offer experienced views an point you to othe observations posters have made about the firm.
Also make sure your partner fully understand the financial implications on them due to your IVA. some companies may say the joint account won't be a problem, then you sign and then at fort review you get stung with a different tune, you want a well regarded firm, they are much and much a same on the surface, its once you dig you find out which ones are only cosmetically good !!
Also make sure to see how each company treats things like bonus payments, the exact calculation used for equity release (ask for example). overtime, if you get it when does it have to be paid.
Most importantly, your budget, you're not just setting a budget for today, but for 4 years plus......