Seeking advice about this is a good idea. Even though the blended or 'rearranged' family is a very common scenario throughout the western world, the fact that it is commonplace doesn't mean that it is a simple matter. Nor does it mean that it can't go very wrong - despite our best hopes and intentions.
In all the happiness of falling in love, it can often seem impossible to imagine that everyone won't share the happiness. But, as you know from your partner's children, this is not the case - and understanding how they feel can make a big difference to how ultimately your relationship with their mother will fare.
It sounds like it would be wise to wait a bit longer before moving in and to spend some time finding out, in discussion with your partner, more about how best to manage in this new environment - in other words to gather as much understanding and information as you can about how it feels for her children right now.
Always remember that this is less about you as a person and more about the predictability of child psychology and the impact of change. Adjustment, grief, and divided loyalties are often around in the aftermath of parental separation. If separated parents are in conflict then these features take longer to resolve and can be intensified by the arrival of a new partner.
The children at 11 and 14 are also at an age where they may well find the thought of a parent having a new intimate life particularly difficult. Added to this they already have to share one parent at a time and they might feel resentful that that meagre share has reduced itself yet again, with you as yet another person competing for precious time with their mother.
I know you are very in love with your partner, but remember that a vital part of her happiness is indivisible from that of her children. However well the two of you get on together, if her children are not happy she will probably find it difficult to relax into your relationship. Get to know the children better - and on neutral territory - and gradually build up your respectful contact with them. Be patient with them. Also, continue to engage in your previous activities and allow space for the family to have time on their own.
Areas like discipline can become flashpoints in the blended family situation and these are just the sorts of discussions that you and your partner need to have before you move in together. Children can react negatively to big change and to feeling that their parent's affection is taken up so their reactive bad behaviour needs to be understood in context - and preferably dealt with by the biological parent.
There are many good courses and books available. Arming yourself with knowledge, awareness and a commitment with your partner to seek help if this new life becomes difficult is the way to proceed.
Once the children are able to trust that you respect their relationships with both of their parents, and that you are not trying to replace their father or take away their mother then there is a good chance that they can build a solid connection with you in your own right.
As with any complex transition or merger in life, thinking strategically and availing yourself with as much information as possible will set you on the right path.
Wanting to understand how best to manage her children's feelings also signals your love and respect for their mum - as I am sure she will tell you.
For more information check out Parenting Through Separation - a free service for all families.