Hi os and welcome to the forum
Being subject to an IVA should not cause you a problem with your request for citizenship, however you should check with the Home Office's help-line to be sure. You can ask this type of question an an anonymous basis.
Having a CCJ is not really classed as having a civil case against you, in terms of the type of cases which migh affect citizenship applications. Was the CCJ set in place after your IVA was accepted by creditors? If so, you should apply to have it removed as no legal actions are allowed to continue once an IVA is in place.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk