COMSOL is a good multiphysics software and has a good UI, but you need to buy its license.
You can also look at OpenFOAM where there is a lot of freedom of writing your own solvers. It is an open source C++ based package with a lot of online tutorials available.
ICMP (Metacomp Technologies http://www.metacomptech.com/index.php/features/icmp) and Fluidyn (http://www.fluidyn.com/fluidyn/) are also good options if you want to go for licensed softwares.
no doubt COMSOL is preferable, but you can also choose Matlab as a multi-physical simulation in "Matlab Simulink". I would be easy to learn too from Matlab library.
If you do modelling of interconnected physical systems that can be described by continuous time ODE I think Modelica is good choice. It is equation based and object oriented and allow non-causal modelling to support more physical modularisation. You can also combine continuous time and discrete time systems. Here is also well-proven libraries of from different branches of engineering. A good open source implementation of Modelica is https://jmodelica.org. There are also various commercial implementations of Modelica available and one in Mathematica called SystemModeler. I can help with more material for those interested and want to get started. / Jan Peter
FEATool Multiphysics https://www.featool.com has been specifically designed to be fast and easy to learn and use. Moreover, the GUI features built-in one-click interfaces for both the FEniCS and OpenFOAM solvers.