Essentially, the barmitzvah boy or batmitzvah girl will be expected to read a piece of Torah and share in the leading of a service on, or just after, their 13th birthday. They will have been expected to have studied the weekly portion from the Torah and comment on it, specifically the bit that he/she will read.

But, above all else, it’s a chance for them to celebrate a turning point in their lives with family and friends.

There is no difference at all. Liberal Judaism affirms the equal status of boys and girls in religious education. Accordingly, we offer both barmitzvah and batmitzvah ceremonies at age 13 or above, in our communities, as part of a Shabbat Morning service.
They will not miss out. Local communities have different practices but will usually expect a child to have attended religion school for a minimum period of a year before their bar/batmitzvah and, in some synagogues, two years.

In your case, your child would simply have their bar/batmitzvah at, perhaps, 15 years of age.

Liberal Judaism treats each person as an individual, and your Liberal rabbi will tailor the marking of the bar/batmitzvah to the needs of your child and the family.
No. It is not a requirement, but many people who have converted to Judaism enjoy the chance to have one and celebrate with family and friends.
Yes, and that is a key part of Liberal Judaism. Recognising that bar/batmitzvah, although significant, does not, in modern society, mark a child’s becoming an adult, the ceremony of Kabbalat Torah at age 15+ allows girls and boys to affirm their commitment to Judaism as a consequence of a personal decision.

Kabbalat Torah is a firmly established religious observance in Liberal Judaism, which encourages students to think about issues through the lens of Jewish tradition and Liberal Jewish values.

Apart from formal learning, most courses include active participation in the religious and cultural life of the community. Students are also invited to participate in events with young people from other communities and on trips to places of Jewish interest in the UK and Europe.

Many post Kabbalat Torah students come back to the religion school to become class helpers, and later a number choose to become teachers.

Yes, absolutely. If you are concerned, please do speak to the congregation’s rabbi, or any officer of the community, beforehand and they can reassure you.