This is the position approved for England and Wales by the Vatican:
Guidelines for Catholics responding to Declaration of Ecumenical Welcome and Commitment from other Churches
“ At the Second Vatican Council the Catholic Church committed herself irrevocably to following the path of the ecumenical venture……” (Ut Unum Sint 3.)
There is, as is well known, a serious obligation for Catholics to attend Mass on Sundays, unless they have reasonable cause not to do so, because the celebration of the Eucharist on the Lord’s Day is at the centre of our Catholic life.
At the Eucharistic celebrations of other Christians (i) Catholics, if invited, may receive a blessing at Communion time (ii), and may;
Read the lesson
Take part in intercessory prayer
Participate in music, dance and drama.
At Non-Eucharistic services of other Christians (iii) Catholics may
Participate in planning and leading the service
Read the lesson and Gospel
Give the address
Lead or take part in intercessory prayer
Participate in music, dance and drama
(i) “It is not permissible for Catholics to receive Holy Communion, or the sacraments of Reconciliation and Anointing of the Sick from ministers of the Anglican Communion, the Church of Scotland or of other faith communities rooted in the Reformation”
One Bread, One Body 117
(ii) “Reciprocal acceptance of a ‘blessing’ by Catholics and other Christians at each other’s Eucharistic celebrations is something which we encourage as a sign of the degree of unity we share”
One Bread, One Body 84
(iii) “At liturgical celebrations taking place in other Churches and ecclesial communities, Catholics are encouraged to take part in the psalms, responses, hymns and common actions of the Church in which they are guests. If invited by their hosts they may read a lesson or preach.
Directory for the Application of Principles and Norms on Ecumenism 118
(iv) Directory for the Application of Principles and Norms on Ecumenism 131,133,134,135.