You should be fine having a movie pass and entertainment pass both active at the same time on your same single username account.
If you wished, you could have all four passes (ie. cinema, entertainment, sports and kids pass on your account active at the same time).
When you go to the Now TV website, click on My Account > My Passes where you can either buy an entertainment and cinema pass or if you wish to save money you can pick up an entertainment voucher code pass and cinema voucher code pass from places like Currys or other various Retailers which you can apply to your account.
Just be aware that you can only have a maximum of four devices and two simultaneous streams on your account.
Any questions don't hesitate to ask.
You are permitted to apply one entertainment and one cinema voucher pass within the last 30 days of the current voucher passes expiring on your account.
When you are within the last 30 day period, you should see a green apply voucher button next to your entertainment and cinema pass on your account which you can check by going to My Account > My Passes on the NowTV website.
Schnapps is quite right when he says you can use an entertainment pass and a cinema pass at the same time, I have done this myself, in the recent past, and I plan to do it again over the Christmas period, i.e. apply my remaining 2 month cinema pass in December while still running my entertainment pass.
You also said, "I have quite a few entertainment passes and movies passes, separate vouchers". I have had a number of entertainment passes, again in the recent past, and I have asked Now TV's help chat to consolidate them for me into 2 x 6 month passes. I have found it much easier to manage, and keep track of, one or two 6 month passes rather than a number of 2 and 3 month ones.
Mind you, I know some forum members will disagree with my approach, primarily because the loss of flexibility in applying passes as and when needed, but I've found that other family members, with their own black box, can watch Now TV without needing to check with me first.